scripted-diff: Avoid interface keyword to fix windows gitian build

Rename `interface` to `interfaces`

Build failure reported by Chun Kuan Lee <ken2812221@gmail.com>
https://github.com/bitcoin/bitcoin/pull/10244#issuecomment-379434756

-BEGIN VERIFY SCRIPT-

git mv src/interface src/interfaces
ren() { git grep -l "$1" | xargs sed -i "s,$1,$2,g"; }
ren interface/            interfaces/
ren interface::           interfaces::
ren BITCOIN_INTERFACE_    BITCOIN_INTERFACES_
ren "namespace interface" "namespace interfaces"

-END VERIFY SCRIPT-

src/qt/bitcoingui.cpp

@@ -30,8 +30,8 @@
 
 #include <chainparams.h>
 #include <init.h>
-#include <interface/handler.h>
-#include <interface/node.h>
+#include <interfaces/handler.h>
+#include <interfaces/node.h>
 #include <ui_interface.h>
 #include <util.h>
 
@@ -74,7 +74,7 @@ const std::string BitcoinGUI::DEFAULT_UIPLATFORM =
 #endif
         ;
 
-BitcoinGUI::BitcoinGUI(interface::Node& node, const PlatformStyle *_platformStyle, const NetworkStyle *networkStyle, QWidget *parent) :
+BitcoinGUI::BitcoinGUI(interfaces::Node& node, const PlatformStyle *_platformStyle, const NetworkStyle *networkStyle, QWidget *parent) :
     QMainWindow(parent),
     enableWallet(false),
     m_node(node),